The invention relates to a device for monitoring and controlling the setting width of individual teeth of saw blades or belt-saw blades, and in particular for controlling the width of the setting made by a setting machine.
German Patent DE 195 17 482 A1 teaches determination of the deviation between an actual setting and a nominal setting via monitoring which does not make physical contact (e.g., opto-electronically).
Typically, opto-electronic monitoring is achieved by line cameras which monitor and record the actual width. If there is a deviation between the actual setting width and a nominal setting width, an automatic correction of the setting machine is made. These cameras are disadvantageous because they are expensive and sensitive to contamination. The cameras must precisely and accurately focus on the region where the actual width is found. Therefore, a considerable maintenance expense arises from adjusting and monitoring of the focus and from the regular cleaning of the camera. Otherwise unusable results are obtained.
It is an object of the invention to provide a device for monitoring and controlling the setting width of individual teeth of saw blades or belt-saw blades, which operates reliably with the least amount of maintenance and manufacturing costs.
The object of the invention is achieved in that the monitoring device comprises at least one photo sensor which emits a light beam at least partly through a monitored region, adjacent to the running saw blade or belt-saw blade, where the set teeth 2 project laterally. Photo sensors are inexpensive to obtain and adjust, as compared to line cameras. A narrow parallel light beam between the light emitter and a light receiver allows the monitored region to be monitored with precise and accurate focus. Because the present invention does not use a lens like line cameras do, there is less chance of contamination, and the maintenance expense that is associated with line cameras is therefore reduced.
Although generally one photo sensor would be sufficient to monitor both sides of the saw blade, by for example using a mirror, a preferred embodiment of the invention includes two photo sensors for monitoring adjacent monitored regions on both sides of the saw blade or belt-saw blade.
The photo sensor may also comprise a laser, which obtains a sharply limited parallel light beam that is well suited for the monitoring of the setting made.
In a further embodiment of the invention, the photo sensor may be designed as a laser scanner, i.e. a light emitter and light receiver are rigidly connected by way of a U-shaped bow.
Such a laser scanner may be assembled on a laterally traversable and fixable carriage in order to be able to simply and safely emit the light beam precisely onto the region to be monitored.
The light beam is preferably emitted at a small angle with respect to the plane of the saw blade or belt-saw blade because an arrangement where the light beam is emitted parallel to the plane of a blade is subject to false or erroneous measurement if there is a backing of the saw or lateral deflection of the saw. If the backing of the saw is caused by a problem with the advancement of the saw, and is laterally deflected, the saw may not be within the region of the light beam. There is however no significant difference with respect to optical conditions between a light beam emitted at a small angle with respect to the plane of the blade and a light beam emitted parallel to the plane of the blade.
In another embodiment of the invention, the cross section of the light beam effective for the monitoring is dimensioned and arranged in a manner such that it essentially encompasses half the belt-saw blade body and the maximum setting width. The region between the middle position of the set tooth and the belt-saw blade body may be monitored, and even corrected if necessary, by way of the light beam that overlaps the belt-saw blade.
Centering is required for a reliable determination of the setting width. In order to ensure centering, a centering device is provided which centers the advancing belt-saw blade with respect to the photo sensors.
The centering device comprises two laterally adjacent jaws which are movably guided perpendicular to the saw blade plane and which are elastically pressed onto the belt-saw blade body in order to guide the belt-saw blade. A mechanical synchronization of a movement of the two jaws in opposite directions is further provided. In this manner the elastically mounted jaws may continuously laterally yield should the thickness of the belt-saw blade change or other lateral forces occur by way of disorder, such as for example by the waviness of the belt-saw blade. It is however always guaranteed that the jaws in each case are displaced by the same path distance, one to the right and the other to the left, so that a thicker belt-saw blade is always led symmetrically to a middle plane lying between the jaws. The jaws in each case are connected to a rack, and the teeth of the rack are in engagement with opposite sides of a pinion.